TMA Installlation Training
Transcript of TMA Installlation Training
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Installation
TMA and Bias Tee
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TMA Installation
Any orientation is ok
TMA is 100% sealed
Connect to the proper ports ANT port to antenna
BTS port to feeder
Separate ground cable?
Ground path exists throughcoaxial cable shield
Use ground wire if in doubt
Follow local practice
Smaller TMAs mount withband clamps, not brackets
Rear Bracket
Flat Washer + Split Lock Washer + Hex Nut
TMA Bracket
Hex Bolt + Flat Washer
Grounding Bolt
Cap Screw for TMA Bracket
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Bias Tee Installation Icebridge
Used with outdoor BTS, including some Lucent ModCell
Bias tee grounding is essential
ABT-DMDF-ADB is most appropriate version
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Bias Tee Installation Top Cap
Used on outdoor BTS, e.g., Alcatel & Nokia
Separate ground may not be necessary
ABT-DFDM-ADB typically used
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Bias Tee Installation Hatch Plate
Installed on end of feeder insideshelter
Replaces lightning arrestor
Grounding is important
Ensure no obstructions to DCcurrent are between bias tee andTMA
No -wave stubs
No RET bias tees
ABT-DMDF-ADB is best fit
Feeder normally ends with femaleconnector
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Bias Tee Installation BTS Cabinet
Used on many indoor cabinets Nokia, Ericsson, others
Surge arrestor recommended at hatch plate
Must be DC passing, such as APTDC series
ABT-DFDM-ADB is used when installed on cabinet port (female)
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Bias Tee Installation with Diplexer
Can be installed at either BTS cabinet
Ensure DC pass through the branch used
Ensure DC block in opposite diplexer branch Diplexer with integrated DC block
Attached external DC block
Disused bias tee with DC cable removed
Installed on diplexer common port is an option
No DC through diplexer blocking not needed
Never attempt to combine DC sources Result will be unpredictable
Can cause equipment damage
Bias tee
Bias tee
DC block
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Power Distribution Unit
Description & Operation
OEM Substitutes
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PDU Construction
Supply voltage depends on model
24 VDC (18-36 VDC)
(-)48 VDC (38-58 VDC)
Input is polarity protected
Output current capability is thesame for all, but normal windowdepends on model, each output
20 3 to 165 5 mA, single-band
175 5 to 312 11 mA, dual-band
PTC resettable fuse on each output
Triggers around 600-1000 mA
Recovers automatically in < 20 s
Single relay alarm output
TMA current outside of window
Supply voltage out of range
DC/DC converter failure
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PDU Front Panel
TMA current OK or alarm disabled
TMA current above or below window
Short circuit or output disabled
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PDU Connections
Alarm Interface pin-out iswith reference to the relayin its de-energized state
Normally open (NO)
terminal is open Normally closed (NC)
terminal is closed
This is the alarm state
Defaults to alarm state ifsupply power is lost
PDU energizes the relay toindicate no alarm
Bias Tee Harness graycable may also be yellow
Power Cable leads areboth black
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PDU Operation
DC OUTPUT dip switches turn output voltage on/off
UP to enable
MHA ALARM dip switches turn current monitoring on/off
DOWN to enable
TMA current out of window for duration > ~2 s activates alarm
Turns green LED off and red LED on
Relay output indicates alarm
Excessive current (> ~800 mA, short circuit) triggers PTC resistor
Relay output indicates alarm
Alarm, once activated, must be reset manually
Turn PDU off and back on
Or use MHA ALARM switch UP to reset DOWN to re-enable
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OEM integrated TMA support
PDU function is built into BTS orNode-B
Bias tees are often detachable
but available from OEM
Ericsson RBS-2206 shown here
TMA support is activated throughthe O&M interface
Procedure varies by BTS type
Compatible with Andrew TMAsbut some exceptions exist
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OEM integrated TMA support
Bias tees connect to a DC outlet panel using a short coax cable
Andrew bias tees can be used in place of OEM in most cases
Andrew offers cables to fit Ericsson and Nokia outlet panels
Ericsson RBS-2206 Nokia UltraSite
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Troubleshooting
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Troubleshooting - Basics
DC problems involve the supply voltage and current to the TMA
PDU alarm is an indication of a DC problem
Alarm from OEM TMA support may not be separable from RF alarms
An RF problem may not exist or may be undetected
Cause of problem can be in DC supply, PDU, bias tee, TMA, or in cablesand connections anywhere in the DC path
RF problems involve the uplink and downlink RF signals
Alarms, if any, are reported from the base station, not the PDU
VSWR alarms are detected at the TX frequencies
Issues with noise levels pertain to the RX frequencies
Cause of problem can be in the BTS, bias tee, TMA, or other RF path
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Troubleshooting DC Problems
Is there a PDU alarm indication?
MHA ALARM must be enabled to obtain alarm indication.
If the DC path was broken, alarms must be reset from latched state.
Green lights nearly always mean there is no DC problem.
Is the PDU the correct model for the TMA?
Are the MHA ALARM switches firmly enabled?
Disconnect the Bias Tee Harness and confirm red lights come on. If they dont,the PDU is defective.
Red lights can indicate a TMA failure or (more often) an open circuit.
Disconnect DC at the bias tee and verify 12 VDC at the cable end. Reconnect.
Disconnect the bias tee ANT port and verify 12 VDC at the port.
Check for any DC blocks in RF path, diplexer, RET devices, etc.
Measure the current in line with the disconnected RF path. TMA in alarm?
Is there a TMA on this feeder? Sweep and look for filter response.
Poorly attached RF connectors? Sweep may look ok even if no DC contact.
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Troubleshooting DC Problems (contd)
Are there fewer than six outputs in use?
Make sure DC OUTPUT and MHA ALARM switches are set as appropriate.
Check Bias Tee Harness color coding to verify used/unused as intended.
No lights indicate a short circuit.
Make sure the DC OUTPUT switches are enabled.
Disconnect DC at the bias tee and measure resistance from bias tee center pinto case. Should be very high or open circuit. Short circuit looks like 1-15 ohms.
High resistance through the bias tee suggests the short is in harness or PDU.
Disconnect the bias tee ANT port and measure resistance of the feeder. Short? Check for any DC shorts in RF path. wave stub (may be part of connector)?
Is there a TMA on this feeder? Sweep and look for filter response.
Is the TMA installed backwards? Will sweep ok but measure DC short.
Remove TMA and measure at BTS port. Short indicates defective TMA.
Remove the bias tee and measure resistance between DC and BTS ports.
Continuity indicates defective bias tee. (DC path was grounded by the BTS.)
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Troubleshooting RF Problems
Does the BTS indicate high VSWR?
Is the alarm threshold set too low?
15.5 dB return loss is a reasonable expectation with multiple elements in path.
Disconnect the bias tee BTS port and sweep through the bias tee with DC to TMA.
If all good, the problem is with the BTS or cabling. Crossed jumpers?
If RX return loss is much better than TX band, problem is on antenna side.Turning off PDU should result in poor RX band return loss.
Disconnect the bias tee ANT port and sweep the feeder. Examine the TX band.
If all good, the problem is with the bias tee.
Is the reflection high and flat with no visible filter response?
Poorly attached RF connectors?
Diplexer misconnected to opposite band port?
Feeder not connected or connected to wrong frequency antenna?
Do a DTF (Distance To Fault) sweep. Any problem with the feeder?
Remove TMA, terminate ANT port and sweep at BTS port. Replace if < 18 dB RL.
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Troubleshooting RF Problems (contd)
Does the BTS indicate a high noise floor?
Have necessary configuration changes, if any, been made?
BTS may need to be programmed with the higher RX path net gain.
Procedure varies with BTS type.
Should an attenuator be installed at the RX port of the BTS duplexer?
This is another way to adjust the net RX path gain which is sometimes used.
Is the attenuator the specified value?
Is the perceived problem an observation of unfamiliar performance statistics?
The data may be as expected.
The performance improvement of the TMA should be possible to validate bylooking at the appropriate parameters.
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Andrew Corporation is the foremost global supplier of one-stop,end-to-end radio frequency (RF) subsystem solutions.